What killed my hen and how do I keep my flock healthy?

A clean coop and good nutritional food for the chickens is important and also using coop bedding materials like hay or pine shavings to soak up urine to prevent ammonia. You should also be feeding your chickens a variety of foods to balance there diet and do daily/weekly checks on all your chickens to make sure they are as healthy as can be. Nothing sterile but clean and healthy.

 

Well here is a sure thing to keep the flock healthy
https://www.backyardchickens.com/th...elping-sick-chicks-or-adult-chickens.1151160/
Glenda Heywood
WET MASH PROBIOTIC RECIPE FOR A SINGLE CHICKEN
IF CHICKEN IS MOULTING AND IS STRESSED DO THIS FOR ITS HEALTH:
ALSO IF TREATING SICK CHICKS OR ADULTS
IE: WORMING, ANY TYPE DISEASE OR COCCIDIOSIS ETC:
...
Glenda Heywood now the
natural probiotic recipe is this:
1 qt of dry crumbles
1 tsp of dry flax seed meal (the kind for huans)
2 qts of milk, sweet, sour, or buttermilk or a mixture of all or some
1/4 cup of non flavored yoguart ( no artificial sweetmer)
mix good.
do not make sloopy JUST WET AND CHICKENS WILL EAT IT BETTER
chickens do not like sloppy feed AS IT STICKS ON THEIR BEAKS.

ADULT CHICKENS
NOW THE IMPORTANT INGRIEDIENT FOR EACH CHICKEN FED
and add 1- 400 mg of Vit E (PER CHICKEN FED WET MASH PROBIOTIC MIXTURE) by cutting the end off the vit E capsule for each chicken fed this wet mash
putting the vitamin E in the wet mash and mix wet mash good to get vitamin E in every chickens amount
this for each chicken your treating
so for each chicken use 4 tsp of mixture and 1-400 mg of Vit E
twice a day for them till the birds feathers are grown out then just three times a week feed wet mash and cut back on the vitamin E to 400 mg once a week
and feed each chicken
4 tsp full of the wet mash probiotic and what they will clean up in 20-30 minutes
then clean wet feeders and restock dry crumbles
IE: or each chicken your making wet mash probiotic for
DO THIS
4 tsp of feed, I/4 tsp of dry flax seed meal,and 1 tsp of the yoguart and just enough milk to mix it good not sloppy wet. And add the 400 mg Vitamin E once a week if not sick
IF SICK (for each chicken fed wet mash now)feed 1 vit E 100 mg cut and put in wet Mash twice a day per chicken that is sick.
Also a Vit B complex, crushed in tbsp. and then add drops of water to dissolve it and add to wet mash.
1-selenium tablet crushed in tbsp. and few drops of water to dissolve it and add to wet mash mixture and stir very good.

CHICKS RECIPE:
DO THIS
IF CHICKS ARE SICK add a 400 mg vitamin E ONCE A DAY TO THE ABOVE: ie: 1 QT OF CRUMBLES AND 2 QTS OF WATER AND 1/4 CUP PLAIN YOGUART
(this is for any and all kinds of sickness ).
DO NOT USE MILK WHEN FEEDING CHICKS USE WATER.
ALSO IF TREATING CHICKENS WHO ARE SICK
DO NOT put Apple Cider Vinegar in the water while giving medication
OTHER WISE use 2 tabelspoons of ACV to the gallon when not feeding medication
Glenda Heywood Cassville Missouri

 

Sorry for your loss.
I would suggest keeping the coop clean and feeding fermented feed.

 

Did you check for lice and mites?

 

Yes they can but I don't think they cause nasty poops.
Worms are more likely.
Have your chickens ever been wormed?
Can you take some fresh poop into your vet and have them do a fecal on it?
It's cheap and quick.

 

No not necessarily, most can't be seen by the naked eye.
And usually you will only see them pass roundworms when they are full of them.